WM8850
Pre-Production
MIC2 (NID = 15h)
Table 18 gives a summary of the MIC2 node:
NODE SUMMARY INFORMATION
15h
NID
Widget Type
Audio Input Converter
Supported Get Verbs
Supported Set Verbs
Unsolicited Responses
Vendor-Specific Verbs
Ah, F00h, F02h, F03h, F06h, F08h, F8Eh, FB1h
703h, 706h, 708h, 78Eh, 7B1h
Stream Drop
F8Eh, 78Eh : Unsolicited Response Priority Control Verb
FB1h, 7B1h : Channel Copy Verb
Table 18 MIC2 Node Summary Information
The MIC2 node supports digital audio input at all common sample rates from 8kHz to 48kHz.
Note that the Stream Format Verb in the MIC2 widget (NID = 15h) is read-only; the associated
parameters will echo the values set in the same verb in the MIC1 widget.
The MIC2 output data is by default set to provide the captured waveform from the left channel in
Channel 0, and the right channel in Channel 1. It is possible to adjust this mapping using the vendor-
specific Channel Copy Verb:
SET VERB
BIT
BITFIELD
NAME
DEFAULT
DESCRIPTION
7B1h
1
CHAN1_
SEL
1
Channel 1 (right) Mapping Control:
0 = Channel 1 takes data from left audio
channel
1 = Channel 1 takes data from right audio
channel
0
CHAN0_
SEL
0
Channel 0 (left) Mapping Control:
0 = Channel 0 takes data from left audio
channel
1 = Channel 0 takes data from right audio
channel
DIGITAL MICROPHONE INTERFACE CLOCK RATES
The sample rate of data captured by the digital microphone interface is controlled by the Stream
Format Verb in the MIC1 widget (NID = 03h). Note that the Stream Format Verb in the MIC2 widget
(NID = 15h) will echo the values set in the same verb in the MIC1 widget. This is necessary as
DMICCLK is shared between the DMICDAT1 and DMICDAT2 pins.
The DMICCLK frequency will output at the rates shown in Table 19, which also contains the required
settings for Base, Mult and Div as part of the Stream Format Verb of the MIC1 widget to obtain the
required sample rate:
SAMPLE RATE
BASE
MULT[2:0]
DIV[2:0]
DMICCLK
FREQUENCY
PROCESSING
RATE
8kHz
11.025kHz
16kHz
0h
1h
0h
1h
0h
1h
0h
0h
0h
0h
0h
1h
0h
0h
5h
3h
2h
1h
2h
0h
0h
1.024MHz
1.4112MHz
1.024MHz
1.4112MHz
2.048MHz
2.8224MHz
3.072MHz
128fs
128fs
64fs
64fs
64fs
64fs
64fs
22.05kHz
32kHz
44.1kHz
48kHz
Table 19 MIC1 Supported Sample Rate Settings for Digital Microphone Interface
Note: Other settings of Base, Mult and Div are reserved and should not be set.
PP, April 2011, Rev 3.2
50
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
